383 runs like a giant turd WTF

[BBBCUDA]

Someone here replied previously with that same thought process...the only forged slugs I know of that would be worth a damn for a 383 would be the Diamond flat tops...nice close to zero deck pistons with healthy reliefs big enough for 2.14/1.81 valves...but you still need small chamber heads...

Downside? They're $600...unless you guys know of some more forgings available elsewhere...seems like there are tons available for 383 strokers and for 400s, and 440s...but nothing nice for a regular old 383

If you run closed chamber heads, and stick to the 2.08/1.74" valve sizes, a stock forged replacement flat top can hit 10.0/1 comp pretty easily. These pistons don't have valve reliefs, and will limit you to right around .510" lift. With well ported heads, 10/1 a .500"+ cam, good intake and exhaust, I could easily see 500HP being made, which isn't too hard to take.

 

[rumblefish360]

With that info, it leads to the old default package for 500 HP. Works awesome in the 440.

OE poster, how are we looking so far? Getting some where

 

[JohnRR]

If you run closed chamber heads, and stick to the 2.08/1.74" valve sizes, a stock forged replacement flat top can hit 10.0/1 comp pretty easily. These pistons don't have valve reliefs, and will limit you to right around .510" lift. With well ported heads, 10/1 a .500"+ cam, good intake and exhaust, I could easily see 500HP being made, which isn't too hard to take.

The pistons would have to be at zero deck and the heads chambers at 80cc , or smaller if one does not deck the block as even the speedpro slug is .015 in the hole in a factory deck block.

Dwayne Porter built a 500HP 383, it had a stock lift cam ... .450 ... with a lot of duration and the heads had no porting at all , he had to cut valve reliefs in the pistons .

 

[BBBCUDA]

The pistons would have to be at zero deck and the heads chambers at 80cc , or smaller if one does not deck the block as even the speedpro slug is .015 in the hole in a factory deck block.

Dwayne Porter built a 500HP 383, it had a stock lift cam ... .450 ... with a lot of duration and the heads had no porting at all , he had to cut valve reliefs in the pistons .

My heads have nail head valves, which eat up cc's over the tulip head factory style valve, and have been milled. Mine CC'd at either 73, or 74 CC's. The no valve notch helps the compression issue too.
Another member here runs the .509 MP cam, and has around .080" valve to piston clearance. Mr. Porter and I have spoken quite a bit, he's not far up the road... He is the one that told me the .528 MP cam has more clearance than the "509" cam.

 

[Abodybomber]

Old heads,cams do work.Just need to remember how designed.Compression,vs rapid rate cams,well ported heads.As long as you realize/recognize that,you good.